<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>取消请求</title>
    <link crossorigin='anonymous' href="https://cdn.bootcss.com/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    <script src="./node_modules/axios/dist/mine-axios.js"></script>
</head>
<body>
    <div class="container">
        <h2 class="page-header">axios取消请求</h2>
        <button class="btn btn-primary"> 发送请求 </button>
        <button class="btn btn-warning"> 取消请求 </button>
    </div>
    <script>
        //获取按钮
        const btns = document.querySelectorAll('button');
        //2.声明全局变量
        let cancel = null;
        //发送请求
        btns[0].onclick = function(){
            //检测上一次的请求是否已经完成
            if(cancel !== null){
                //取消上一次的请求
                cancel();
            }

            //创建 cancelToken 的值
            let cancelToken = new axios.CancelToken(
                function(c){
                    //3. 将 c 的值赋值给 cancel
                    cancel = c;
                });

            axios({
                method: 'GET',
                url: 'http://localhost:3000/posts',
                //1. 添加配置对象的属性
                cancelToken: cancelToken
            }).then(response => {
                console.log(response);
                //将 cancel 的值初始化
                cancel = null;
            })
        }

        //绑定第二个事件取消请求
        btns[1].onclick = function(){
            cancel();
        }
    </script>   
</body>
</html>